The Genesis account shows that God determined to cleanse the earth of wickedness by deluging the planet with water. He told Noah to construct an ark in order to preserve himself, his family, and representatives of the animal world through this great Flood. God told Noah to make the ark 300 cubits long, 50 cubits wide, and 30 cubits high. (Genesis 6:15) According to one conservative estimate, this would make the ark about 438 feet [134 m] long, 73 feet [22 m] wide, and 44 feet [13 m] high.a It thus had a gross volume of some 1,400,000 cubic feet [40,000 cu m].

Good Seakeeping

The ark’s length was six times its width and ten times its height. Many modern ships have similar proportions, although for them the length-to-breadth ratio is chosen with regard to the power required to move them through the water. The ark, on the other hand, had only to float. How well would it have performed?

The manner in which vessels respond to wind and waves is called seakeeping behavior. This too is related to a vessel’s proportions. The Bible describes the tremendous downpour that produced the Flood and also says that God later caused a wind to blow. (Genesis 7:11, 12, 17-20; 8:1) The Scriptures do not say how strong the waves and wind were, but likely both wind and waves would have been powerful and changeable, even as they can be today. The longer and harder the wind blows, the higher and farther apart are the waves. In addition, any seismic action could have produced strong waves.

The ark’s proportions contributed to its stability, preventing it from capsizing. The ark was also designed to deal with the forces that could cause it to pitch lengthwise in heavy seas. Extreme pitching​—when each wave lifts one end of the vessel and then allows it to plunge downward—​would have been very uncomfortable for the people and animals on board. Pitching also puts heavy stresses on a vessel. The structure must be strong enough to resist the tendency to sag in the middle when large waves lift both ends of the vessel at the same time. Yet, when a large wave lifts the vessel at its midpoint, with nothing to support its ends, the bow and stern may bend downward. God told Noah to use a length-to-depth ratio of 10 to 1. Later shipbuilders would learn only by hard experience that such a ratio can accommodate these stresses.